It is well known in the art that repeated washing of cotton-containing fabrics generally causes a pronounced, unpleasant harshness in the fabric, and several methods for overcoming this problem have previously been suggested in the art. For example U.S. Pat. No. 1,368,599 of Unilever Ltd. teaches the use of cellulytic enzymes for reducing the harshness of cotton-containing fabrics. Also, U.S. Pat. No. 4,435,307 (of Novo Industri A/S) teaches the use of a cellulytic enzyme derived from Humicola insolens as well as a fraction thereof, designated AC.sub.x I, as a harshness reducing detergent additive. Other uses of cellulytic enzymes mentioned in the art involve soil removal from and colour clarification of fabric (cf. for instance EP 220 016).
Although the use of cellulytic enzymes for harshness reduction of cotton-containing fabrics was suggested and demonstrated nearly 20 years ago the mechanism of this process has not been elucidated and is still not known in detail. Among other things, this is due to the multiplicity of the enzymes and the enzyme-catalyzed reactions involved. As a matter of fact, cellulases generated in nature e.g. by microbial species are indeed complex mixtures of cellulytic enzymes. Accordingly, the conversion of naturally occurring materials, like cotton, catalyzed by cellulases is exceedingly difficult to analyze in detail.
Due to these circumstances the practical exploitation of enzymatic harshness reduction and prevention, however desirable, has not become widespread and of great practical utility: it is difficult to optimise production of multiple enzyme systems and thus to implement industrial cost-effective production of cellulytic enzymes, and their actual use has been hampered by difficulties arising from the need to apply rather large quantities of the cellulytic enzymes to achieve the desired reduction and prevention of the harshness of cotton fabrics: for instance, addition of large quantities of the enzymes to detergent compositions is not compatible with the optimal function of other ingredients in the detergent formulation nor is the addition of very large quantities of enzymes to the detergent composition in the interest of e.g. consumer safety.